Electronic throttle bodies are generally known, and are used for controlling the flow of air into an engine. These throttle bodies have some type of valve, which is typically a valve plate disposed in a port of a housing, which is rotated to increase or decrease the amount of air flow into the engine. Electronic throttle bodies typically have a “default air flow” setting, which is achieved by setting a specific opening angle of the throttle plate relative to its fully closed position. A final gear (such as a sector gear), is mounted on a shaft along with the throttle plate, and the sector gear is used to rotate the shaft and throttle plate.
The default air flow is achieved by including the use of an opening spring connected to the sector gear, where the opening spring is supported by a spring stop inside the sector gear and a default stop located in the housing. Many design requirements include specifying the tolerance of the opening angle of the valve plate to be ±0.1°, and in some instances, less than ±0.1°.
During assembly, the sector gear is mounted to the shaft, the throttle plate is in a fully closed position, and the sector gear is positioned such that the opening spring places the gear against a gear stop. Positioning the valve plate to have the desired default air flow setting requires a significant amount of effort.
One of the solutions to provide proper adjustment of the valve plate is to use set screws, either to set the default stop position of the valve plate or the gear stop position. However, using set screws has the disadvantage that the screw diameter must be larger than the end of the spring, and large enough to guaranty the proper connection to the appropriate component attached to the throttle body. This results in the diameter of these set screws being too large to position them properly inside the gearbox. Therefore, the screws must be driven for rotation from outside of the gearbox. After assembly, the set screws must be secured and the access holes for the set screws must be closed off to ensure the set screws remain properly positioned and cannot be manipulated.
Accordingly, there exists a need for a throttle body which incorporates the ability to adjust the default air flow setting of the valve plate, without the drawbacks mentioned above.